Food processing equipment and food contact surfaces (e.g., tables and countertops) require sanitization or disinfection between food preparations, particularly when processing raw food such as cutting meat, in order to prevent cross-contamination and the spread of food-borne diseases. In addition, non-food contact surfaces benefit from sanitization and disinfection to limit pathogen loads and the spread of potentially infectious agents (e.g., in hospital, industrial, commercial, or household settings). Food processing equipment is often cleaned using one solution and then sanitized/disinfected with a separate solution. The solutions described in this invention allow the same solution to be used for cleaning and sanitizing/disinfecting since the solution has good cleaning power and strong antimicrobial efficacy. Sanitization greatly reduces the bioburden (e.g., bacteria, yeasts, molds, viruses) on the food or non-food contact surface and thereby reduces the likelihood of the spread of microbial diseases. Disinfection provides an even greater reduction in the amount of bioburden and in turn an even greater reduction in the likelihood of the spread of microbial diseases. The sanitizing/disinfecting solution described in this invention has the ability to function as a sanitizer and a disinfectant.
Many sanitizing and disinfecting compositions have been developed. Many are not approved for food contact surface use since they are formulated with ingredients that would be harmful if their residues on the food contact surface were transferred to food and were subsequently ingested by humans. Sanitizing and disinfecting compositions that are acceptable for food contact surface use are often corrosive to the food processing equipment or food contact surface since they often contain chlorine, chlorine dioxide, chlorinated or halogenated compounds, peracetic acid, or other corrosive ingredients. Therefore, there is a need for a low toxicity, non-corrosive sanitizing/disinfecting solution for food and non-food contact surface use.
Various patents have disclosed the antimicrobial properties of low pH (acidic)-anionic surfactant formulations, with some of the patents disclosing the use of low pH-anionic surfactant formulations on food contact surfaces. U.S. Pat. No. 6,953,772 discloses a food contact surface sanitizing solution including at least lactic acid and phosphoric acid, an anionic surfactant, and a sequestering agent. U.S. Pat. No. 5,143,720 discloses anhydrous sanitizing/disinfecting compositions including an acid and an anionic surfactant, and includes example anhydrous (dry) formulations including an acid, an anionic surfactant, and low concentrations of short chain fatty acids, although the purpose of including the fatty acids in the anhydrous formulations is not described. U.S. Pat. No. 4,715,980 discloses a food contact surface sanitizing composition including a dicarboxylic acid, another acid, and an anionic surfactant. U.S. Pat. No. 5,280,042 discloses food contact surface sanitizing and disinfecting compositions against cyst or oocyte forms of protozoa including an anionic surfactant and an acidic component. U.S. Pat. No. 6,867,233 discloses an acidic antimicrobial composition for use on food contact surfaces including an organic acid, an anionic surfactant, polypropylene glycol, and a carbonate. U.S. Pat. No. 7,851,430 discloses a food contact surface disinfecting composition containing an organic acid, an anionic surfactant, and a buffering agent.
U.S. Pat. No. 6,262,038 discloses a germicidal composition including a mixture of alpha-hydroxy fruit acid, anionic surfactant, and sophorose lipid biosurfactant for use on skin or hair. U.S. Pat. No. 5,490,992 discloses a disinfectant composition including a fatty acid monoester, an acid, and an anionic surfactant for use on poultry carcasses.
U.S. Pat. No. 4,404,040, discloses formulations for sanitizing dairy and brewery equipment using a solution comprising an aliphatic short chain fatty acid, a solubilizer (e.g., an anionic surfactant), and an acid. This patent further discloses the optional use of alcohols at low concentrations (≤0.2%) to help reduce the viscosity of the final concentrated solution.
A major limitation of the referenced low pH-anionic surfactant concentrate formulations is that their efficacy (cleaning ability and antimicrobial activity) may be adversely affected when diluted with hard water (e.g., water containing at least 300 ppm hardness ions such as calcium and magnesium, and especially at least 500 ppm hardness ions). Anionic surfactants such as sodium lauryl sulfate often have better hard water tolerance than soaps (saponified fatty acids); however, anionic surfactants may still suffer from reduced efficacy in hard water due to the formation of insoluble compounds when complexed with the calcium and magnesium ions typically present in hard water. In addition, acid-anionic surfactant formulations are inherently unstable due to hydrolysis of the anionic surfactant. This is particularly problematic at higher temperatures that may be encountered during storage of the product. It is accordingly an object of this invention to provide a stable, naturally-derived sanitizing/disinfecting solution that retains efficacy in hard water. In addition, the solution should exhibit low human and environmental toxicity and be non-corrosive.